JPH01195232A - Method for detecting completion of melting of iron-containing cold charge - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the time of completion of melting of iron-containing cold material.

[Conventional technology] A large amount of iron-containing cold materials such as scrap and shaped pig iron are charged into a converter in which a seed metal such as blast furnace hot metal or high carbon molten iron exists, and oxygen is supplied from a top blowing lance to the bottom of the converter. The method for melting iron-containing cold materials to obtain molten iron by blowing in carbon materials such as coal powder and coke powder and oxygen is described in Japanese Patent Publication No. 56-8085.
It is known from the publication No.

[Problems to be Solved by the Invention] In the method for melting the iron-containing cold material, the bottom blowing of the carbonaceous material and oxygen is stopped at the same time as the melting of the iron-containing cold material is completed. material, the amount of oxygen can be minimized.

However, in the past, the ratio of the amount of seed metal to the amount of iron-containing cold material charged at the time of charging (hereinafter referred to as charging SM ratio), the amount of top blown oxygen for each melting process or melting heat, and the bottom blown gas (oxygen and carbonaceous carrier gas) ) No method has been proposed for simply and accurately detecting the dissolution completion time when operating conditions such as amount change.

The present invention was made in view of the above-mentioned circumstances, and provides a method for simply and accurately detecting the melting completion time of iron-containing cold material even when operating conditions change.

[Means for Solving the Problems] The gist of the present invention is to charge iron-containing cold material into a converter in which a seed metal exists, supply oxygen from a top blowing lance, and supply carbonaceous material from a tuyere at the bottom of the converter. In a method for melting iron-containing cold materials in which molten iron is obtained by blowing oxygen into the iron-containing cold materials, the low-frequency component vibration force and the full-frequency component vibration force of the furnace body vibration of the converter are determined as n'', and both of the above-mentioned This method calculates the ratio of vibration forces and determines that the iron-containing refrigerant has been completely melted when the ratio reaches a preset value. Low frequency component vibration force and high frequency component vibration force of body vibration? In this method, the melting completion timing of the iron-containing cold material is determined by calculating the ratio of the two vibration forces and determining that the iron-containing cold material has completely melted when the ratio reaches a preset value.

The present invention will be explained in detail below.

In an oxygen top-bottom blowing converter that decarburizes blast furnace hot metal, the furnace body vibrates due to the flow of molten steel, and the vibration component is a low frequency component (usually 0 .3 to 0.4 Hz) and higher frequency components (3 to 4 Hz or less).

In the present invention, the liquid level sloshing is suppressed by the iron-containing cold material present in the molten iron, and the degree of suppression is determined by the ratio of the amount of molten metal during the iron-containing material removal process to the amount of the iron-containing cold material (hereinafter referred to as molten SM ratio). This was based on the new knowledge that it changes depending on

Figures 1 to 3 show iron-containing cooling in which a large amount of iron-containing cold material is charged into a converter containing seed metal, and oxygen is blown in from the top blowing lance and carbonaceous material and oxygen are blown in at a constant rate from the tuyeres at the bottom of the furnace. Power spectrum distribution of the furnace body vibration in the converter during the initial, middle, and final stages of melting of the material (more specifically, the power spectrum distribution obtained by processing the output of the strain gauge installed on the trunnion bearing frame of the furnace body with a fast Fourier transformer) This is what is shown.

When the iron-containing refrigerant starts to melt, there is a large amount of solid iron-containing refrigerant, so the entire liquid level does not fluctuate greatly, and as shown in Figure 1, it reaches zero.
．． The vibration intensity of the low frequency waves of 3 to 0.4 Hz is low, but as the melting progresses, the entire liquid level begins to oscillate, and as shown in Figure 2, the vibration intensity of the low frequency waves increases, and when complete melting, the liquid level Since the entire device oscillates greatly, the low frequency vibration intensity reaches its maximum value as shown in FIG.

That is, the vibration intensity of the low frequency of 0.3 to 0.4 Hz changes depending on the dissolution rate of the iron-containing cold material, and the dissolution rate increases.

Therefore, the vibration intensity increases. On the other hand, the vibration intensity of the high frequency of 3 to 4 Hz is the natural frequency of the mechanical system, so it hardly changes depending on the dissolution rate of the iron-containing cold material.

Further, the power spectrum distribution shown in FIGS. 1 to 3 shifts up and down depending on the amount of top blown oxygen and the amount of bottom blown gas, but the pattern does not change even if the amount of top blown oxygen and bottom blown gas changes. Further, depending on the charging SM ratio, the power spectrum distribution at the initial stage of melting becomes the pattern shown in FIG. 1 or FIG. 2.

Therefore, a specific frequency of 1.5-0.5Hz, e.g. IH
The vibration force obtained by integrating the vibration intensity of frequencies below z (
(hereinafter referred to as low frequency component vibration force) and the vibration force obtained by integrating the vibration intensity of all frequencies (hereinafter referred to as full frequency component vibration force) [(low frequency component vibration force/full frequency component vibration force)] or (full frequency component vibration force/low frequency component vibration force)],
Alternatively, the vibration force obtained by integrating the vibration intensity of a frequency of 1 llz or less (low frequency component vibration force) and the vibration force obtained by integrating the vibration intensity of a frequency of IHz or higher (hereinafter referred to as high frequency component) (referred to as vibration force) ratio [(
The relationship between low frequency component vibration force/high frequency component vibration force) or (high frequency component vibration force/low frequency component vibration force)] and the dissolution rate of the iron-containing material is determined in advance, the above vibration force is measured, and the above ratio is determined. is calculated, and the ratio is the dissolution rate 1 determined in advance.
When the ratio reaches 00%, it can be determined that the iron-containing cold material has completely melted.

Changes in the charging SM ratio only result in the power spectrum distribution at the initial stage of melting becoming the pattern shown in Figures 1 or 2, and furthermore, changes in the amount of top-blown oxygen and bottom-blown gas during the melting process or each melting heat are , the power spectrum distribution is shifted up and down, but even if the power spectrum distribution is shifted up and down, the ratio of the vibration force does not change, so according to the method of the present invention, the time of completion of melting is determined from the ratio of the vibration force. Even if operating conditions such as the charging SM ratio, the melting process, the amount of top-blown oxygen for each melting heat, and the amount of bottom-blown gas are changed, the timing of completion of melting of the iron-containing cold material can be detected with high accuracy.

FIG. 4 shows an embodiment of the melting completion time detection device of the present invention for detecting the melting completion time of a ferrous cold material from (low frequency component vibration force/full frequency component vibration force).

1 has a top-blown oxygen lance (not shown), and a concentric triple tube nozzle (inner tube 2 N2. carbon material nozzle) at the bottom of the furnace.

A strain gauge 100 equipped with a tuyere (not shown) consisting of an inner tube: an oxygen nozzle and an outer tube: an LPG nozzle is installed on the trunnion bearing support frame 3 of the converter 2, and converts the furnace body vibration into an electrical signal. be.

4 is a low pass filter (LPF) that passes low frequency components below IHz, 5 is a peak holder that receives the output signal of LPF 4 and outputs the low frequency component vibration force, and 6 receives the output signal of strain gauge 1. A peak holder that outputs the input vibration force of all frequency components of the furnace body vibration, 7 is the ratio of the low frequency component vibration force to the total frequency component vibration force (
8 is a comparator that outputs a melting completion signal when the ratio reaches a preset value in the ratio setting device 9.

Note that the detection device may be constructed by embedding a load cell in the support frame instead of the strain gauge.

Figure 5 shows the relationship between the above ratio (low frequency component vibration force/full frequency component vibration force) and the dissolution rate of the iron-containing cold material. Charge the material,
Sampling the molten iron during the melting process, and
It was calculated by analyzing the concentration.

Therefore, in the dissolution time detection device shown in FIG. 4, by setting the ratio setter 9 to 0.5, the dissolution completion time can be accurately detected even if the operating conditions change.

[Effects of the Invention] As described above, according to the method of the present invention, the timing of completion of melting of the iron-containing cold material can be detected easily and accurately even if the operating conditions change.

[Brief explanation of the drawings] 1st. Figure 2.3 shows a large amount of iron-containing cold material being charged into a converter containing seed water, and oxygen being blown in from the top blowing lance and carbonaceous material and oxygen being blown in at a constant rate from the tuyeres at the bottom of the furnace. Early stage of dissolution,
Figure 4 is an explanatory diagram of the power spectrum distribution of the furnace body vibration of a converter in the middle and final stages, and the present invention is used to detect the melting completion time of iron-containing cold materials from (low frequency component vibration force/full frequency component vibration force) Explanatory diagram of an embodiment of the dissolution completion time detection device, No. 5
The figure is an explanatory chart of the relationship between (low frequency component vibration force/full frequency component vibration force) and the dissolution rate of the iron-containing cold material. 1: Strain gauge 2: Converter 3: Trunnion bearing support frame 4: Low pass filter 5: Peak holder 6 = Peak holder 7 = Calculator 8: Comparator 9: Ratio setting device
Patent attorney Tatsuo Chanoki / 2'
34 5 Frequency (//Z) Figure 4

Claims (1)

[Claims] 1. Charge iron-containing cold material into a converter in which seed water is present, and blow oxygen through the top blowing lance and carbonaceous material and oxygen through the tuyere at the bottom of the converter to cool the iron-containing cold material. In the method of melting iron-containing cold material to obtain molten iron by melting the material, the low-frequency component vibration force and the full-frequency component vibration force of the furnace body vibration of the converter are measured, the ratio of the two vibration forces is calculated, and the A method for detecting the completion time of melting of a ferrous refrigerant, characterized in that it is determined that the ferrous refrigerant has been completely melted when the ratio reaches a preset value. 2. Charge the iron-containing cold material into the converter where the seed water is present, and blow in oxygen from the top blowing lance and carbonaceous material and oxygen from the tuyeres at the bottom of the converter to melt the iron-containing cold material and produce molten iron. In the method for melting iron-containing cold materials, the low-frequency component vibration force and the high-frequency component vibration force of the furnace body vibration of the converter are measured, the ratio of the two vibration forces is calculated, and the ratio is set to a preset value. A method for detecting the completion time of melting of a iron-containing cold material, characterized in that it is determined that the iron-containing cold material has completely melted when .